Having trouble combining 2 functions

I am currently a student in high school. Due to the fact that my state is on complete shutdown because of the whole COVID-19 crisis that is going on. I am trying to add 2 functions into a range of cells to further organize myself while trying my best to stay organized doing school from home.

Function 1: =DAYS(E:E,TODAY()) Count how many days left to complete an assignment.

Function 2: =IF(E:E=-1, "PAST DUE") If the amount of days left equals -1, it will change the cell text to "PAST DUE".

The only problems I am having is A: Combining 2 functions, and B: making the IF statement work. If there is any way you could help me out, then please try. It would mean a whole lot.